Swivel chair



Jam.Y l, 1935. T, w. Foo-rE 1,986,105

SWIVEL CHAIR 6 Sheets-Sheet l Filed April 22, 1952 n BY y ATroRNEY Jan. 15 1935. T. w. FooTE 1,986,105

swIvEL CHAIR Filed April 22, 1952 6 Sheets-Sheet 2 O c v 55mg a 22 5' E 9 30 .mamas W- FOU'E INVENTOR EL ATTORNEY.

Jam 1, 1935- T. wf Foo-rE 1,986,105

SWIVEL CHAIR l Filed April 22, 1932 6 Sheets-Sheet` 5 n ww i@ ATroRNEY Jan'. 1, 1935. 1w, F'OOTE 1,986,105

SWIVEL CHAIR Fued Apri 22, 1932 e sheets-sheet 4 Y' A l g a@ 1 2,2 6.2151 [63 404,59

Tho'mo W 599+? INVENTOR a ATTORNEY TQ w. FooTE Jan. 1, 1935.

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T. W. FOOTE Jan. l, 1935.

SWIVEL CHAIR Filed April 22, 1932 6 She/ets-Sheet 6 N vENToR 15*A AfrroRNEY Patented Jan. 1, 1935 UNITED STATES PATENT OFFICE.

SWIVEL CHAIR Thomas W. Foote, Cleveland, Ohio Application April 22, 1932, Serial No. 606,850

. 9 Claims. (Cl. 155-77) My invention relates to improvements in chair the modification of Figure 3; Figure 8A is a subirons used in connection with revolving and tiltstantially transverse sectional view taken on lines ing chairs and has reference particularly to a 8 8 of Figure 7 Figure 9 is another substantially chair iron which embodies in its construction intransverse sectional View taken on lines 9-9 of dependent and adjustable resilient supports for Figure 7; Figure 10 is a side elevational view of 5 the seat and back rest, the chair back; Figure 11 is a front elevational The principal object of the invention is to proview of the same with parts shown in section to vide a new and improved means, adjustably condisclose the spring pivotal mounting for the back trolled, for supporting a swivel seat and the back rest; Figure 12 is a substantially longitudinal secrest ofachair, so as automatically to adjustthemtional View of one embodiment of the pivotal 10 selves relatively of each other to accommodate mounting taken on lines 12-12 of Figure 10; Figthe occupant in a comfortable position. ure 13 is a DGISDGCVG View 0f allOther embOdi- Another object of my invention is the provision ment of the spring pivotal connection for the of a new and improved spring hinge mechanism back rest; Figure 14 is a substantially longitudi- 15 for mounting the back rest on the back standards nal sectional view of the pivot according to Fig- 15v of typewriter or oice chairs so that said rest may 111'@ 13; Figi-11'@ 1 5 iS e Side elevational VieW 0f a automatically adjust itself to the most comfortthird modification of pivotal connection for the able position for the occupant when in use. back rest; Figure 16 is a substantially longitudi- A still further object of this invention is the nal sectional view taken on lines 1616 of Fig- 20 provision of a seat construction which is provided ure 15; Figure 17 .is a, substantially longitudinal 20 with a part solid surface and part cushioned sursectional view of a second embodiment of the upface whereby greater ease is afforded the occuper bearing for the sleeve on the shaft or spinpant dle; and Figure 18 is a similar view of a third Still another object of the invention resides in embodiment of the upper bearing unil? fOI the the ball bearing pivotal support of the chair iron sleeve of the chair iron. 25 in which the shaft does not revolve in the hub, Referring to the drawingsY and particularly to thereby permitting proper height adjustment. the chairs shown in Figures 1, 2 and 13, 10 de- And still another object of the invention fito notes a seat portion mounted for support upon a provide the seat with arm rests which are'jpcite chair iron 11, which is rotatably carried upon a independent of the back rest so as to enable-fthe pedestal 12 and which is adapted to support the 30 latter to adjust itself to the comfort of the occu-- back member 13. pant without interference from the arm rests. Chair seat I accomplish these objects by means of the combinations and arrangements of parts herein- 36 after described in the specification, set forth in the appended claims and illustratively exemplied in the accompanying drawings, in which Figure 1 is a perspective view of 'one embodiment of 'A my improved chair construction with the seat re- 40 moved; Figure 2 is a perspective view of the seat and cushiontherefor; Figure 3 is another per- ,spective view'of a chair illustrating a slightly modified construction for the chair iron; Figure 4 is 'a top plan View of the chair iron according to TRS the arm rests 1 8 Whlh consist. of upnght that used in Figure 1; Figure 51s a subscentiauy 311116119519 Secured m uprlght 13051151011 0n each 45 longitudinal sectional view taken on lines 5 5 of Slde of the bottom towards the f ront and 0f Figure 4; Figure 5a is a substantiallytransverse L'ShaPed member? arrajnged at the ends Pon sectional view taken on lines 521-5a of Figure 5; the-spmdls 19 and agamst the .wan 15 at pomts Figure 6 is a substantially longitudinal sectional d jaceniiiih fffar 0f the Seat- The chair seat 10, illustrated in Figure 2, comprises a seat section having its forward or front 35 portion 14 of a solid piece of wood suitably shaped to afford comfort to the occupant. The solid piece terminates along a line drawn transversely of the seat and disposed just forward of the center thereof, the remaining portion comprising a marginal wall 15 and perforated bottom piece 16 to provide a Well. A cushion 17 having the approximate shape of the well is placed therein. The seat carview on a larger scale than that of Figure 5 show- 'f Chair iron 50 lng the ball bearing chair iron construction in de'- tail; Figure 6x11 is a substantieuy transverse see- The Seat 10 1S Supported upon the chalr iron and tional View taken on lines 6**--61L of Figure 6; Figin the present instance the latter, according toA ure 7 is a substantially longitudinal sectional view Figures 1 and 4 t0 7 COmpriSeS a Spider 20 C011- u. of the chair iron constructed in accordance with sisting of two spaced angle bars arranged parallel on opposite sides of an imaginary longitudinally disposed center line, the outer end portions of the bars being flared outwardly and bent slightly upwardly and are provided with screw holes 21 to receive screws driven into the under side of the bottom of the seat. The outside flanges of the spider bars are directed downwardly and at their mid portions are rigidly attached to the depending sides of an inverted U-shaped plate 22, the cross piece thereof projecting under the lateral flanges of thespider bars and forming a saddle to bridge the space therebetween. The lower ends of the depending sides of the plate 22 are pivotally supported upon a pin 23 which is carried :by a second U-shaped plate 24 and projects at its ends through the upright arms of the latter plate at a point adjacent the rear side thereof and on an elevation of less than half the height of the said arms. The U-shaped plate 24 is reenforced just above the pin 23 by an inverted U-shaped bracket 25, which ts just inside the arms of the plate 24 and has its depending arms rigidly secured thereto and pierced by the pin 23.

The chair iron swivels about an upright shaft 26 supported on the pedestal 12 and turns in a sleeve bearing 27 permanently arranged in and projecting through the closed ends of the' U- shaped plates 22 and 24, as illustrated particularly in Figure'6, the sleeve 27 being preferably closed at its upper end.

The angle bars of the spider 20 adjacent their rear ends are riveted to the opposite ends of a metal bridge piece 28, the mid portion thereof being stamped out to accommodate the head of a bolt 29. The threaded stem of the bolt 29 hangs downwardly and projects through the opening in the closed end of an inverted U-shaped strap 30, the depending arms of which are integrally attached to the inner sides of lever arms 31, which are pivotally mounted on a pin 32 at their forward ends, and which pivotally support a back iron 33 at their free ends. The pin 32 is fixed between the depending arms ofthe bridge piece 22, by projecting through the latter and linto the upright flanges of the angle bars of the spider 20. The pin 32 projects transversely of the imaginary longitudinal center line of the chairA iron in the space between the upper closed end of the bearing sleeve 27 and the closed end of the saddle plate 22 so that the back 13 is adjustable about an axis directly over the axis of the shaft 26.

i Adjustment of the back 13 is effected by means of a anged hand wheel 34, which is carried by the threaded stem of the bolt 29, and which is movable thereover to compress or release the tension of a helical spring 35 surrounding the bolt and having a washer 36 at opposite ends to abut ithe hand wheel 34 and under side of the closed end of the strap 30. Downward adjustment of the back is limited by the upper sides of the lever arms 31 which sides are curved downwardly beyond the pivot pin 32 and abutv the under face of the saddle 22 whenthe lower limit has been reached.

In addition to an adustment of the back, the same may be tilted and the tilting mechanism comprises the back iron or stirrup shaped bracket 33 embracing the free ends of the lever arms 31 and being pivoted thereto on studs 38 fixed in the arms adjacent their mid portions, the studs being projected into the depending arms of the strap 30 to add strength to the pivotal connection. The bracket 33 is movable about its pivotal axis so as to ybring the closed end in more or less upright position, the closed end or back portion of the bracket 33 being provided with a raised rib 39 having a longitudinally disposed slot 39a for the purpose hereinafter described. Tilting action of the bracket 33 is controlled by a screw 40 which is arranged parallel to the back portion directly forward of the rib 39 and which ,turns in a threaded transverse bore 41 of a rod 42 journaled at its ends in and between the free ends of the lever arms 31. The screw 40 is provided at its lower end with a hand wheel 43 having an elongated hub 44 abutting and turning with the screw against the under surface of an L-shaped piece 45 attached to and arranged as an integral part of the closed end of the bracket 33 at its inner face. Above the angle piece 45 the screw is provided with a washer 46 and cotter pin 47 to prevent the screw from doing more than to turn in the angle piece. In accordance with this arrangement, rotary adjustment of the screw 40 in the bar or rod 42 will cause the stirrup bracket 33 to swing about its pivotal connection on the lever arms 31.

Referring now to the spring tension for balancing the tilting of the seat about its pivot pin 23, it will be seen that the forward edge of the bridge piece or saddle 22 is bent downwardly at an angle to form a lip 48 having a slot 49 projecting from a point adjacent its lower end upwardly through the angle and into the body of the saddle where it terminates in an enlarged semicircular opening 50. The opening 50 allows the head of a bolt 5l to slide through to a position against the rear face of the lip, the threaded stem of the bolt projecting forwardly along the longitudinal center line of the iron to a point about opposite the extreme forward ends of the spider arms 20.- A hand -wheel 52 is adjustably carried on the outer end of the bolt 51 to control the tension of a helical compression spring 53 embracing the bolt, the inner end of the spring abutting a plate 54 having a central opening 55 to accommodate the bolt 5l. Each end of the plate 55 is provided with a triangularly shaped recess 56 to receive a tooth 57 projecting forwardly from the forward side of each upright arm of the U-shaped plate 24.

The operation of the foregoing spring tension device is such that when the weight of the occupant is thrown towards the back of the chair, the seat and spider arms 20 rock about the pin 23 as a center and in doing so, the saddle 22 and lip 48 follow the movement of the seat, whereupon the bolt 51 is drawn towards the rear. The hub of the hand wheel 52 forming an abutment for one end of the spring 53 causes the latter to compress under tension, because the opposite end of the spring is more or less stationary, being disposed against the plate 55, which merely rocks in the recesses 56 of the plate 24. Therefore, as the bolt 51 is drawn rearwardly the hand wheel 52 compresses the spring and the latter offers a resilient support against pressure to rock the seat to the rear. The degree of resistance to this rocking movement is controlled by the relative adjustment of the hand wheel 52 with respect to the end of the bolt.

Referring now to the modied construction of the chair iron illustratively exemplified in Figures 3, "I, 8 and 9, 20 denotes the spider consisting of the two spaced bars and 22 the saddle which is rigidly secured to the lateral and upright flanges of the said angle bars of the spider. The saddle 22 consists of an upper wall forming the bridge piece between the two bars of the spider, side walls depending from the upper wall and pivoting on the ends of apin 23' carried by a U-shaped plate 24', and a rear Wall 58, in which there is an opening 59 disposed centrally thereof and adjacent the corner between the top and rear Walls, and in which there are vtwo slots 60, each thereof being arranged parallel to and adjacent one of the upright corners between, the side and rear walls. Adjacent the lower ends of the slots 60 and disposed just inside the line of each is a small round opening 61. The U-shaped plate 24 is provided with a reenforcing inverted U-shaped strap 25 which is spaced above the closed bottom wall 0f the plate 24' and which receives and is attached to the upper end of the revolving sleeve 27 of the swivel base or pedestal 12, a portion of the same sleeve being keyed to and projected through the bottom wall of the plate 24.

The spring tension and adjustment of the back of the chair, comprises a pair of extremely heavy coiled springs 62 disposed loosely about a pivot pin 32 carried by the sides of the plate 22' and depending flanges of the spider bars 20. The outer end of each spring 62 bears against the under side of the top portion of the plate 22 and the opposite ends of the springs project rearwardly through the opening 59 and into the grooves inthe under side of a plate 63. The plate 63 is provided with a center opening to accommodate a bolt 64, the head thereof being disposed against-the upper side of the plate 63 while the stem projects downwardly and receives a hand wheel 65 at its lower end.

The springs 62 are tensioned by adjustment of the hand wheel 65 the hub of which bears against the under surface of a U-shaped tie plate 66 carried by a pair of spaced lever arms'31 pivotally mounted at their forward ends on the pin 32'. The lever arms 31 project rearwardly through the slots 60 in the rear wall 58 of the plate 22' and beyond the tie plate 66 to receive the ends of the bar or rod 42'.

The equipment for accommodating the back, including the tilting mechanism therefor, is the same-as that used in connection with the embodiment of my invention illustratively exemplified in Figures 1, 4 and 5, and no further description of the parts already set forth appears necessary.

Referring now to the resilient tilting mechanism for the seat, 67 denotes a pair of heavy coiled springs which loosely encircle the pivot pin 23 and have their outer ends projecting rearwardly and` through the openings 61 in the wall 58 of the plate 22', and which at their opposite or inner ends extend forwardly-and downwardly to rest in the grooves of a plate 68, the latter being supported in practically upright position on a bolt 69 over which it is adjustable to tension the springs 67. The bolt 69 is L-shaped, the head being arranged against the under face of the closed end of the U-shaped supporting plate 24', while the adjacent shorter arm portion of the stem projects through an opening in the plate 24 and the longer arm portion projectsforwardly between the ends of the springs 67 and through the opening in the mid portion of the plate 68 to accommodate a hand wheel 70 which is adjustable against the plate 68 and over the threaded end of the bolt.

In operation, any pressure brought to bear upon the rear of the seat to tilt it will cause the spider and saddle plate 22 to rock rearwardly on the pivot pin 23' and in doing so,` the ends of the springs 67 in the openings 61 will be forced downwardly with the plate 22' to tension them suiiciently to bring the seat back to its upright position when released.

It will be noted particularly in connection with the seat that the resilient spring support therefor operates quite independently of the spring sup porting mechanism for the back 13.

Swivel support for the chair iron In accordance with my invention I provide a ball bearing support for the chair iron and the various embodiments of this construction are illustratively exemplified in Figures 3, 6, 17 and 18 of the drawings. The characteristic feature of all forms of my construction resides in the suspension of the chair iron from a bearing placed at the upper end of the shaft 26. Referring particularly to Figures 3 and 6, in this connection, the rotary bearing sleeve 27 forming part of and revolving with the -chair iron 11 is preferably closed at its upper end, and arranged in the sleeve adjacent the closed end thereof is a ball bearing unit 71 to receive the specially turned end of the shaft 26. Figure 6 shows the foregoing construction particularly clearly and in this embodiment the shaft 26 is provided with a comparatively long bearing surface which insures smooth rotary movement of the sleeve 27 about the shaft. The sleeve 27 adjacent its lower end is provided with a set screw 72 which projects into an annular groove 73'in the shaft 26 and prevents the sleeve from beingwithdrawn from the shaft 26. The lower end of the shaft 26 below the groove 73 is threaded to receive a collar or hand wheel 74 which is rotated to adjust the height of the shaft and chair. In addition to the threads the lower portion of the shaft 26 is provided with a longitudinally disposed keyway 75.

The collar or hand Wheel 74 comprises an externally knurled annular portion and a raised center portion to increase the thickness of the material at the bore thereof and provide a suflicient-number of threads adequately to engage and support the shaft 26 and chair carried thereby. An annular skirt portion 76 depends from the under side of the wheel and carries a radially disposed set screw 77, which in operative position projects below the vlateral flange 78 of a hub barrel 79, the same being supported upright in the bore of the wood or metal base or pedestal 12, made up of radially v'disposed legs 80, andconnecting filler blocks 81. The barrel 79 is integral with a plate 82 at'a point spaced below the flange 78, the plate resting upon the upper ends of the legs and being secured thereto by means of screws 83 `disposed at the corners and driven into the legs. YThe flange 78 of the barrel 79,is provided at diametrically opposite sides with notches 84 into whch project similarly disposed teeth 85 of a lock washer 86, the latter being interposed between the flange 78 and under the inside wall of the hand wheel 74. The washer 86 embraces the threaded portion of the shaft 26 and is provided with a tooth or key 87 projecting inwardly from its inner periphery to engage in the keyway 75. In operation the hand wheel 74 may be rotated to raise or lower the shaftA 26, but it will be particularly noted that this adjustment involves no more than the rotary movement of they wheel itself because the shaft 26 is only capable of upright` longitudinal movement in the barrel 79,

due to the lock Washer 86 and its connection with the shaft and barrel 79. v

In the constructionexemplied in Figure 17, the upper end of the shaft 26e supports the sleeve 27rl by means of a pin 88 which is carried axially of the closed upper end of the sleeve and arranged to rest upon and rotate about the upper end of the shaft. In Figure 18 the upper end of the shaft 26b is provided with a centrally disposed bearing is placed and arranged to support the sleeve 27h, which rests upon the ball. In each `embodiment of this invention I provide a support for the revolving sleeve 27 of the chair iron at the up'per end of the shaft 26 and I utilize a substantial length of the shaft immediate the upper,

end to form a bearing for the sleeve.

Chair back Referring to the chair back, reference will be had to Figures 1, 3, 10 to 16. In the embodiment illustrated in Figures 1, 3 and 10 to 12, 91 denotes the uprights forming supports for a hinged back rest 92. The uprights91 are spaced apart and at their lower ends they are attached to the ends of a metal strap or rbar 93, which forms' a bridge between the uprights and which at its mid portion is provided with a transverse channel or groove 94 having an opening 95 midway of its length. In assembled position the bar 93 is placed against the bracket 33 of the chair iron and the rib 39 arranged in the groove 94. Abolt 96, with its head held between thewalls of the rib 39 on the inner side of the bracket, is projected through the slot 39a and opening 95 to receive a hand wheel 97 which when tightened down against the bar 93 rigidly holds the latter and bracket together. The upright s lot 39a provides for adjustment of the back to a higher or lower position with respect to the seat.

The uprights project to an elevation corresponding to the lower end of the back rest 92 and on their outer sides each upright carries'a metal extension plate 98 which projects beyond the upper end of the upright and supports a pivot screw 99. The screw 99 projects inwardly and into a iside upright 100 ofthe back 92, the upright 100 forming virtually a continuation of the upright 91 in the normal position of the rest 92.

So far, the construction includes a hinge connection between back uprights 91 and the back rest`92, but it is desirable to provide spring means to return the back rest to normall position when freed from an adjustment taking it temporarily out of alinement. To accomplish this purpose I have contemplated three constructions, one thereof being detailed in Figures10 to 12, comprising a face plate 101, which fits into a recess in the outer surface of the side upright 100 and which is provided with angularly disposed ears disposed flush with adjacent faces of the latter upright to firmly fix its position therein. The upper end of the plate 101 is provided with an opening to accommodate the pivot screw 99 so that the hinge action really takes place about the portion of the screw projecting through the two adjacent plates 98 and 101. The plate 101 is further fixed lin the upright 100 by means of screws 102 which have their heads counters/unl: in the plate and their stems screwed into the upright. The resilient or spring means utilized to return the back rest to normal position comprises a pin 103 mounted onthe inner face of the extension plate 98 and projected into a slot 104 in the plate 101 against a follower 105 slidably mounted in a pocket 106, which is formed by a channel strip 107 arranged between the two ears of the plate 101, and which accommodates a coiled compression spring 108 abutting at one end against an ear of theplate and at the other end against the follower 105. The slot 104 is designed to accommodate the pin 103 in its arcuate movement about the pivot screw 99 as an axis, so that as the upper portion of the backrest swings rearwardly the pins 103 will each hold one end of its spring stationary to compress it as the opposite end is swung forwardly towards the pin. l n

Referring now tothe hinge construction illustrated in Figures 13 and 14, the pvot screw 106 in each extension or plate 98 projects through a block 107 rigid on the inner face of the plate 98 and then through a channel shaped housing 108', loosely embracing the parallel straight sides of the block 107', and finally into the wood of'th'e upright 100 of the back rest. The housing 108 and block 107' are disposed in a recess in the upright 100, the recess being tapered to a point on opposite sides of the housing to accommodate and confine the opposite ends of a hairpin spring 109, the mid portion thereof embracing closely the opposite straight sides of the block 107', so that as the back rest swings out of alinernent and with it the ends of the springs 109, the distortion thereof will take place about the corners of the stationary blocks 10'7' which will compel the springs to right themselves when released and return the back rest to normal position.V An advantage of this construction is that the back rest may swing either forwardly or backward and be returned to normal position by the springs 109.

The third embodiment of my spring hinge connection for a back rest is constructed especially for a chair back in which the uprights 91 are not provided 'with the extension rods or plates 98. but act themselves as the direct supports for the back rest as illustrated in Figures 15 and 16. In accordance with this arrangement the uprights, designated 110, reach upwardly to embrace substantially one half the outer sides of the side upright portions 100 of the back rest and between the two adjacent uprights on opposite sides of the back, a spring hinge unit is mounted. -Each unit comprises a pair of L-shaped plates 111 arranged with their longer arms face to face and provided with a pivot 112 adjacent their upper ends'. The shorter arms of the plates 111 project in opposite directions' and are secured in the adjacent rear faces of the two uprights 101 and 100 respectively, by means of screws 113. The ends of the longer arms yopposite their pivot connection 112 are each formed into a half round channel shaped wall 114 which is closed at its free end by a semi-circular wall 115. When assembled the two walls 114 form a tubular barrel to accommodate .a coiled compression spring 116. In operation, displacement of the back rest about its pivotal axis will cause the sections or plates lllcarried by the rest to swing relative to the plates' being carried by the uprights 101 and in doing so the effective length of the spring housing formed by the walls 114 will shorten to compress the spring 116. When the back rest is released the springs 116 expand and force the sections or plates 111 of the hinges to right themselves whereby the back rest assumes its normal upright position between the uprights 101.

In the foregoing description, I have set forth in detail the operation of the various instrumentalities which are here combined to make a single unit, namely, a swivel desk or stenographers chair embodying a ball bearing chair iron, which revclves about an upright shaft or spindle 26 upon a thrust top bearing arranged at the upper end of the shaft. This construction has the further advantage that the shaft does not rotate -in the hub of the pedestal, whereby proper upright longitudinal adjustment of the shaft may be effected by merely rotating the hand wheel or collar 74 which is prevented from riding up on the shaft because of the set screw 7'7 being engaged under the flange 78 of the hub 79. Another element which forms the essential part of the combination resides in the separate spring supports for the seat and back, whereby the tilting action of each part is entirely independent of the other. This affords the occupant a maximum of comfort because the back will itself automatically yield its position to accommodate any tilted position assumed by the seat. In each case the spring tension may be regulated by adjustment of the hand wheel 34 or 52 in one embodiment of my invention and hand wheel 65 or 70 of the modification illustrated in Figures 3, and 7 to 9. The arrangement of springs 35 and 62 in Figures 5 and '7, respectively, is of particular importance because, the tension in each instance is directed to yieldably support the back against movement downwardly about its pivotal connection with the seat. The last element which renders the chair seat and back almost entirely form fitting is the spring hinge connection for the back rest 92, which when the seat is tilted to just the correct angle and the back swings about its pivotal connection to a proper inclination, it only requires that the back rest itself assume a certain relative position with respect to the back and seat proper to give the occupant a maximum of support.

Having now describedmy invention and the manner in'which the same operates, what I claim and desire to secure by Letters Patent is:

1. In a swivel chair of the character described,vr

the combination with a chair base and an axially adjustable screw shaft supported against rotation in the base, of a chair iron supported on the upper end of the shaft and mounted to revolve on the latter, comprising a seat support mounted to tilt on said iron, a spring connection to yieldably support the seat in normal position, and a back for the chair hinged vto the chair iron and yield-A ably supported in normal position.

2. In a swivel chair of the character described, the combination with a chair base and an axially adjustable screw shaftl supported against rotation in the base, of a chair iron supported on the K upper end of the shaft and mountedto revolve on the latter, comprising aseat support mounted to tilt in said chair iron, a spring connection to yieldably support the seat in normal position, and a back for the chair hinged in the chair iron and yieldably supported in normal position, comprising a back rest hinged to the back of the chair and yieldably supported in normal position.

3. In a swivel chair of the character described, the combination with a chair base and an axially adjustable screw shaft supported against rotation in the base, of a chair iron rotatably mounted on the shaft and supported from the upper end thereof, comprising a seat support mounted totilt in said chair iron, an adjustableA spring connection to yieldably support the seat in normal position, a back support mounted to tilt in said chair.

pivotally carried by the seat spider, and a spring adjustably tensioned to yieldably retain the bracket in normal position.

5. In a swivel chair of the character described, comprising a chair base having an axially adjustable shaft, and a chair iron rotatably mounted on the shaft, comprising a' sleeve embracing the shaft and bearing on the upper end thereof, the combination of a supporting member rigid on said sleeve, a seat spider pivotally mounted to tilt rearwardly 'on the supporting member, a bolt carried by the forward end of the spider, a plate through which the bolt projects seated against the supporting member,l a spring embracing'the bolt and disposed at one end against the plate, and a hand wheel adjustable over the bolt and against the opposite end of the spring to tension the same and retain the spider in normal position. I

6. A swivel chair, as claimedin claim 5, including a back supporting bracket pivotally mounted on the spider, a bolt carried by the latter and projecting downwardly through said back bracket, a hand wheel adjustably carried at the lower end of the bolt, and a spring embracing the bolt and disposed between the hand wheel and the back bracket to yieldably support the same in normal position.

7. A swivel chair, as claimed in claim 4, including a stirrup embracing the rear of the vback bracket and hinged to the latter, the closed end disposed transversely to the turning axis of the stirrup, a hand controlledscrew turning in and carried by the closed end of the stirrup linside the rib thereof, a bar carried by the back bracket and provided with a transverse threaded bore to receive the screw, whereby rotary adjustment of the latter will raise or lower the stirrup about its hinged axis, and aback having a bar at its lower end provided with a groove having an opening to receive the rib of the stirrup, and means carried by the stirrup and projecting through the slot of the latter and the opening of the groove to x the back bar along the slotted rib.

8. A swivelchair, as claimed in claim 4, including a stirrup embracing the rear of the back bracket and hinged to the latter, the closed end oi' the stirrup being providedwith a rib and slot, disposed transversely to the turning axis of the stirrup, a hand controlled screw turning in and carried by the closed end of the stirrup inside the rib thereof, a bar carried by the back bracket and provided with a transverse threaded bore to receive the screw, whereby rotary adjustment of the latter will raise or lower the stirrup about its hinged axis, and a back having a bar at its lower end provided with a groove having an opening to receive the rib of the stirrup, and means carried by the stirrup and projecting through the slot of the latter and the opening of the groove to x the back bar along the slotted rib, said back comprising uprights carried by the backv bar, and a back rest pivotally supported at the upper ends of the uprights. v

9. A swivel chair, as claimed-in claim 4, including a stirrup embracing the rear of the back bracket and hinged to the latter, the closed end of the stirrup being provided with a rib and slot, disposed transversely to the turning axis aof the stirrup, a hand controlled screw turning in and carried by the closed end of the stirrup inside the rib thereof, a bar carried by the back bracket' and provided with a transverse threaded bore to receive the screw, whereby rotary adjustment of the latter will raise or lower the stirrup about its hinged axis,-'and a back having a bar at its lower end provided with a groove having an opening` to receive the rib of the stirrup, and means carried by the stirrup and projecting through the slot of the latter and the opening ofthe groove to x the back bar along the slotted rib, said back comprising transversely divided uprights carried by the 

